package com.khd.problems_0001_0100;

/**
 * 21. 合并两个有序链表
 *
 * @author kehandi
 * @title: Problem_0021_MergeTwoSortedLists
 * @projectName algorithm
 * @date 2022/6/5 17:27
 */
public class Problem_0021_MergeTwoSortedLists {

    public static ListNode mergeTwoLists(ListNode list1, ListNode list2) {
        if (list1 == null) return list2;
        if (list2 == null) return list1;

        if (list1.val < list2.val) {
            list1.next = mergeTwoLists(list1.next, list2);
            return list1;
        } else {
            list2.next = mergeTwoLists(list1, list2.next);
            return list2;
        }
    }

    public static class ListNode {
        int val;
        ListNode next;

        ListNode() {
        }

        ListNode(int val) {
            this.val = val;
        }

        ListNode(int val, ListNode next) {
            this.val = val;
            this.next = next;
        }
    }

    public static void main(String[] args) {

    }
}
